Ray Dolby, the US engineer who founded Dolby Laboratories and pioneered noise reduction in audio recordings, has died in San Francisco aged 80. Mr Dolby had suffered from Alzheimer's disease for several years and was diagnosed with leukaemia this summer. His name became synonymous with home sound systems and cinema, and his work won many awards.Mr Dolby was born in Portland, Oregon, and grew up in the San Francisco area. He began his career in the Ampex Corporation, helping to develop early videotape recording systems while he was still a student. He then went on to complete his PhD at Cambridge University in England and in 1965 founded Dolby Laboratories in London. The company grew to be an industry leader in audio technology, cutting background hiss in tape recordings and later bringing out "surround sound". Mr Dolby moved his company to San Francisco in 1976 and in 1989 was awarded an Oscar for his contributions to cinema. He shared the award with Dolby executive Ioan Allen.He also received a Grammy award in 1995 and Emmy awards in 1989 and 2005.